Headrests for vehicle seats are required to be adjustable vertically. Pivotal adjustment principles are shown by such patents as U.S. Pat. No. 4,304,439 issued Dec. 8, 1981 to Terada. Horizontal headrest movement for vehicle seats is shown by U.S. Pat. No. 4,191,422 issued Mar. 4, 1890 to Insawa. Horizontal movement of headrest for barber chairs is shown by such patents as 2,434,007 issued to F. O'Dea Jan. 6, 1948 and 2,460,942 to A. Marshall on Feb. 8, 1949.
Also, the patent to Gregory U.S. Pat. No. 4,295,681 discloses a two link arrangement mounted on oppositely threaded shaft portions for extending and retracting a lumbar support and the patent to Kashihara et al. U.S. Pat. No. 4,469,374 discloses another two link arrangement on a threaded shaft for causing a tilting motion of a portion of a seat back.
These patents show many types of movement for a headrest and seat back ranging from gear actuated linkages (Terada), rack and pinion (Insawa), pivoted link (O'Dea), pantograph structures (Marshall) and threaded rod actuated links (Gregory and Kashihara et al.).